He was a Quebec Conservative Party leader but never premier. First elected to the Legislative Assembly in a by-election in 1882 in the riding of Laval, he served as leader of the Opposition from 1905 to 1908, when he lost the 1908 election and his own seat. Served as the 11th Lieutenant Governor of Quebec from February 12, 1915 until his death in Montreal 1918.
Prior to his political career, Leblanc was a teacher and a lawyer
He lost the 1908 election.